Tissue Microvessel Density as a Potential Predictive Marker for Vascular Invasion in Colorectal Cancer

This study aimed to determine whether microvessel density (MVD) in the tumor tissues could be a potential predictive marker for vascular invasion (VI).

Surgical specimens of 73 patients with colorectal adenocarcinoma in Phramongkutklao Hospital were analyzed. Tissues of patients receiving preoperative radiation or prior anti-angiogenic therapy were excluded. Tumor MVD was determined using the average number of counted CD34-stained endothelial cells from two selected fields at 200x magnification in each slide. The presence of VI was defined by tumor involvement of endothelial cell-lined spaces. The optimal cut-off value of MVD to predict VI was examined using receiver operating characteristic analysis to assess the area under the curve and accuracy.

VI was detected in 17 of 73 specimens (23.3%). Colorectal cancer (CRC) specimens were classified according to MVD as low (61 specimens, 83.6%) and high density (12 specimens, 16.4%). Average MVD was slightly higher in specimens with VI (81.3±9.3) than those without VI (76.3±7.6), but without statistical significance (p = 0.736). The MVD's cut-off value of 60 vessels/200x field provided 88% sensitivity, 40% specificity, and 57.5% accuracy, with the area under the ROC curve of 0.5788. Patients with CRC having MVD of > 60 vessels/200x field were at significantly higher risk of VI than those with CRC having MVD of <60 vessels/200x field (P=0.009, Fisher's exact test). Univariate analysis revealed that MVD, nodal involvement and AJCC tumor stage were associated with the presence of VI (p <0.05). Further multivariate analysis of these three potential variables demonstrated MVD (OR, 11.994; 95% CI, 2.197 to 65.483; p <0.01) and nodal involvement (OR, 10.767; 95% CI, 1.973 to 58.748; p <0.05) as independent prognostic factors associated with VI.

Based on our study, MVD immunostaining was an angiogenic marker that potentially be a predictive marker for VI.